In the Once Heavily Polluted Chicago River, More Fish, a Giant Snapping Turtle and an Upcoming Swim

CHICAGO—Krystyna Kurth likes to begin her tours of the river cutting past the city’s post-industrial area with a word association game.

Kurth, coordinator of conservation action at the Shedd Aquarium, first began leading Kayak for Conservation tours of the Chicago River’s North Branch six years ago. When she started, the first words about it that came to mind for kayakers were “dirty” or “green,” either drawing on the river’s perceived swampiness or its emerald-dyed St. Patrick’s Day celebrations. Other associations had similarly negative connotations, from “polluted” to “dead bodies.”

Now Kurth says she’s hearing more positive associations, like “diversity,” that reflect the river’s cleaner turn and wide range of wildlife. That remarkable transformation is thanks to a combination of federal regulations, improvements to the city’s sewage system and a floating wetland project spearheaded by the local nonprofit Urban Rivers with help from the aquarium.

Signs of the river’s better health include visits from “Chonkosaurus,” a giant snapping turtle who’s a global social media sensation. Chicago is so optimistic about the river’s improvements that the city plans in a few weeks to hold its first open water swim downtown in nearly a century. The tradition halted in the 1920s due to sewage polluting the water.

The river has come a long way since the days it bore the brunt of the city’s industrial might. 

Before train transportation, barges shipped goods to Chicago. To make way for large boats, the city dredged the waterway and installed steel walls, turning the river into a rectangular box and eliminating the gradual slope of the riverbed. The harsh environment wiped out the underwater plants that created habitats for fish as well as flora that pollinators frequented. 

All that was left was a deep, silty river depleted of its natural resources.

For years, the city also treated the Chicago River as a dump much like the alleys where residents deposited their waste, a convenient place to get rid of pollution, urine and excrement, Kurth said. If you take an architecture tour on the river downtown, you’ll notice many older buildings’ windows do not face it, she adds.

“Really, the river was the alley. It was gross. You didn’t look at it, even think about it. You sent that water away,” Kurth said. “You had all your windows facing the lakefront, but the river was not something that you liked to be around.”

The Chicago River reached a low point in the 1970s. At that time, only five species of fish could survive in the polluted waters, Kurth said, including common carp, largemouth bass, goldfish, bluntnose and the gizzard shad.

In 1972, Congress passed the Clean Water Act, boosting the health of rivers across the country. Among its provisions, the act made it illegal to dump pollutants into navigable waters without a permit. 

Those provisions, which jumpstarted the river’s revival, are now under threat: In March, the U.S. Supreme Court’s conservative majority handed down a ruling that weakened the U.S. Environmental Protection Agency’s authority under the Clean Water Act. 

It’s thanks in part to that law that the number of fish species recorded by the Metropolitan Water Reclamation District in the Chicago River leapt from 10 to 77. 

Austin Happel, research biologist at the Shedd Aquarium, credits the number and diversity of fish species now found in the river to dramatic decreases in sewage-related contaminants as officials upgraded wastewater treatment. Through its Tunnel and Reservoir Program (TARP), Chicago has added a massive amount of storage for stormwater and sewage that might otherwise end up in the river. Researchers studying the river have noticed far fewer fecal coliforms, bacteria related to raw sewage, and harmful nitrogen compounds like ammonia. 

“The fish changed,” Happel said, “because the water is cleaner due to cleaner sewage management practices.”

Fish aren’t the only ones more attracted to the river now. The North Branch has turned into a hot piece of real estate. Kurth points to a former industrial building that now houses upscale offices. At the north end of Goose Island, Mars Wrigley constructed a 44,000-square-foot research and development facility with a rounded tower evoking a lighthouse overlooking the river. Further south, the former Morton Salt warehouse now hosts a music venue dubbed “The Salt Shed.”

Kurth would like to see the same transformation on the South Branch, which abuts neighborhoods that have suffered more environmental injustices than their North Side counterparts.

“I want to continue to see the awesome shifts we’re seeing here on Goose Island, where we see recreation and wildlife and industry kind of all living in a way that makes sense for everyone in a fair way,” she said.

Some vestiges of the industrial age hang on. Concrete companies dot nearby Elston Avenue and as the aquarium’s kayaks glide down the North Branch, you smell the sickeningly sweet whiff of garbage from a neighboring dump. But paddle further down and you’ll come across a new conservation area that’s become a peaceful park for locals.

“The Wild Mile” to the east of Goose Island bills itself as the world’s first ever floating eco-park. Its buoyant boardwalk is made of pontoons that house around 35 different species of native plants on top and root systems underneath that filter heavy metals out of the water. Urban Rivers started funding the program in 2017 and by the following year, the Shedd Aquarium began partnering on the first set of wetlands. At a length of about 700 feet, the public space isn’t nearly a mile yet, but its stewards hope to keep building out.

The cleansing roots help deal with a major problem in urban waterways known as excess nutrients. Agricultural runoff into waterways carries phosphorus and nitrogen into the Mississippi River, which cause huge algal blooms that choke out other life. Urban areas in the Midwest like Chicago not only deal with that agricultural pollution, but city residents’ waste.

“So if you throw your pizza crust on the street or your dog poops and you don’t clean it up, all of that nutrition eventually ends up in the waterway because it’s the lowest point in the landscape,” said Sage Rossman, community outreach and programs manager at Urban Rivers.

The native plants in the Wild Mile rely on phosphorus and nitrogen, their roots sequestering much of that excess and regulating the water, Rossman said. That stretch also includes submerged modules that create an artificial river bottom, restoring those areas destroyed by the giant rectangular box that created mucky buildup unsuitable for native mussels. The artificial river bottoms allow Urban Rivers to put native freshwater mussel species back into the ecosystem.

“Our submerged modules have become home to a slew of other wonderful river creatures as well,” Rossman said. “There’s probably about 20 pumpkinseed and bluegill fish nesting in that area. It’s packed to the brim with it.”

It’s not just local environmentalists gushing over the Wild Mile’s progress. As Kurth’s group kayaks past jewelweed growing by the boardwalk, they stop to talk to Levi Lundell, a Ph.D. student at the University of Saskatchewan in Canada. Lundell first learned about the Wild Mile in class when students gave presentations on innovative restoration projects. 

“In restoration and conservation spaces, there’s a tension of ‘we want to put this back the way it was’ and often that baseline, people think of as ‘no people,’ which isn’t really reasonable in the city,” said Lundell, looking at the native plants on the floating dock. “The way they seemed to embrace ‘we want to bring these plants back’ but do it in a way that lets people be there, I think that’s the main thing I was impressed by and want to see happen in more places. It’s a very pragmatic project.”